I am not entirely sure that I understand what you are trying to do. For example, are there meant to be 6 (random) dice rolls, two rolls or 6 pairs of two dice rolls? As \x is looping over 1,...,6 I think that there might be 6 dice rolls but perhaps this is meant to indicate that standard dice have the numbers from 1 and 6 on the, or not...:)

My first impression was that you wanted something like this (a plot of 6 random dice throws):

Here the dots have been placed randomly using \pgfmathrandominteger using the code: